The Role of Urinary NGAL in the Management of Primary Vesicoureteral Reflux in Children

Persistent Elevation in Urinary Neutrophil Gelatinase-Associated Lipocalin Levels Can Be a Predictor of Urinary Tract Infection Recurrence or Persistence in Women

Women commonly experience urinary tract infection (UTI) recurrence. However, there is no effective tool for predicting recurrent UTI after the first UTI episode. Hence, this study aimed to investigate potential urinary inflammatory biomarkers and specific biomarkers for predicting UTI recurrence or persistence after antibiotic treatment in women. Forty women who had a history of recurrent UTI within 1 year after the initial episode and acute bacterial cystitis were treated with broad-spectrum antibiotics for 1 week. To measure inflammatory biomarker levels, urine samples were collected at the baseline and after 1 week, 1 month, and 3 months. The levels of urinary pro-inflammatory proteins such as neutrophil gelatinase-associated lipocalin (NGAL), nerve growth factor, CXC-motif chemokine ligand (CXCL)-1, interleukin-8, CXCL-10, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha were measured using commercial kits. Seven healthy age-matched women were included as controls. The changes in urinary biomarker levels at the baseline and various time points were compared between women with and without UTI recurrence within 1 month or within 3 months after the initial antibiotic therapy. At the baseline, patients with a higher urinary white blood cell count had a significantly higher NGAL level than the controls and those with a low white blood cell count. Of the 40 patients with a history of recurrent UTI, 12 presented with UTI persistence or recurrence within 1 month and 19 within 3 months after the initial antibiotic treatment. Among the 28 patients without UTI recurrence at 1 month after treatment, 7 had UTI recurrence within 3 months. Compared with patients without UTI recurrence, those with UTI recurrence had significantly higher urinary NGAL levels at 1 week, 1 month, and 3 months after the initial treatment. This study concludes that persistent elevation in urinary NGAL levels after the initial antibiotic treatment indicated persistent bladder inflammation. Further, it could be a predictor of UTI persistence or recurrence within 1 or 3 months after the initial antibiotic treatment. Patients with a history of recurrent UTI and high urinary NGAL levels after antibiotic treatment might require a longer treatment duration to completely eradicate or prevent UTI recurrence.

Biomarkers for urinary tract infection: present and future perspectives

A prompt diagnosis of urinary tract infection (UTI) is necessary to minimize its symptoms and limit sequelae. The current UTI screening by urine test strip analysis and microscopic examination has suboptimal diagnostic accuracy. A definitive diagnosis of UTI by urine culture takes two to three days for the results. These limitations necessitate a need for better biomarkers for the diagnosis and subsequent management of UTI in children. Here, we review the value of currently available UTI biomarkers and highlight the potential of emerging biomarkers that can facilitate a more rapid and accurate UTI diagnosis. Of the newer UTI biomarkers, the most promising are blood procalcitonin (PCT) and urinary neutrophil gelatinase-associated lipocalin (NGAL). PCT can provide diagnostic benefits and should be considered in patients who have a blood test for other reasons. NGAL, which is on the threshold of clinical care, needs more research to address its scope and utilization, including point-of-care application. Employment of these and other biomarkers may ultimately improve UTI diagnosis, guide UTI therapy, reduce antibiotic use, and mitigate UTI complications.

A Multimodal Fuzzy Approach in Evaluating Pediatric Chronic Kidney Disease Using Kidney Biomarkers

Chronic kidney disease (CKD) is one of the most important causes of chronic pediatric morbidity and mortality and places an important burden on the medical system. Current diagnosis and progression monitoring techniques have numerous sensitivity and specificity limitations. New biomarkers for monitoring CKD progression have been assessed. Neutrophil gelatinase-associated lipocalin (NGAL) has had some promising results in adults, but in pediatric patients, due to the small number of patients included in the studies, cutoff values are not agreed upon. The small sample size also makes the statistical approach limited. The aim of our study was to develop a fuzzy logic approach to assess the probability of pediatric CKD progression using both NGAL (urinary and plasmatic) and routine blood test parameters (creatinine and erythrocyte sedimentation rate) as input data. In our study, we describe in detail how to configure a fuzzy model that can simulate the correlations between the input variables ESR, NGAL-P, NGAL-U, creatinine, and the output variable Prob regarding the prognosis of the patient's evolution. The results of the simulations on the model, i.e., the correlations between the input and output variables (3D graphic presentations) are explained in detail. We propose this model as a tool for physicians which will allow them to improve diagnosis, follow-up, and interventional decisions relative to the CKD stage. We believe this innovative approach can be a great tool for the clinician and validates the feasibility of using a fuzzy logic approach in interpreting NGAL biomarker results for CKD progression.

Assessment of Urinary and Serum Neutrophil Gelatinase-Associated Lipocalin (NGAL) Levels as Novel Predictors for Vesicoureteral Reflux Diagnosis in Children with Febrile Urinary Tract Infection

Background

The invasive, expensive, and time-consuming nature of radiological examinations for vesicoureteral reflux (VUR) has compelled researchers to search for new markers to predict VUR. This study was designed to evaluate the usefulness of serum and urine concentrations of neutrophil gelatinase-associated lipocalin (NGAL) in predicting the existence of VUR.

Methods

This cross-sectional study involved all patients with a first febrile urinary tract infection (UTI) referred to Ali Asghar Children's Hospital. Each patient included in the study had clinical symptoms of pyelonephritis and a positive urine culture. The patients were divided into 2 groups: VUR and non-VUR. The serum and urinary NGAL levels were calculated in both groups. The receiver operating characteristic (ROC) curve was used to look for serum and urinary NGAL cut-points that differentiated the VUR group from the non-VUR group.

Results

Among the 40 children in the study, 23 belonged to the VUR group. The median age was 2.5 years (range, 0.3-8 years), and 35 patients were girls. ROC curve analysis showed that only the urinary NGAL level was significantly related to VUR. There was no association between serum NGAL levels and VUR. According to the ROC curve, a urinary NGAL level cut-off value of 15 ng/mL was likely to be diagnostic of VUR with 82.6% sensitivity and 58.8% specificity.

Conclusion

The urinary NGAL level, specifically with a cut-off value of 15 ng/mL, can indicate the existence of VUR in patients with UTI with near-acceptable levels of sensitivity and specificity.

The Utility of Noninvasive Urinary Biomarkers for the Evaluation of Vesicoureteral Reflux in Children

Vesicoureteral reflux (VUR) is one of the most important disorders encountered in pediatric nephrology due to its frequency and potential evolution to chronic kidney disease (CKD). The aim of our study was to identify noninvasive and easy-to-determine urinary markers to facilitate the diagnosis and staging of VUR. We performed a cross-section study including 39 patients with VUR followed over three years (August 2021-September 2023) and 39 children without urinary disorder (the control group). We measured the urinary concentration of interleukin-6 (IL-6), cathelicidin (LL-37), and neutrophil gelatinase-associated lipocalin (NGAL) in VUR and healthy controls. Moreover, we analyzed the correlation between these biomarkers and the presence of renal scars (RS), reflux nephropathy (RN), and CKD. The NGAL concentrations were significantly higher in patients with VUR than in the controls (p = 0.02). Regarding the severity of the reflux, NGAL/creatinine and LL-37/creatinine were positively correlated with severe reflux (p = 0.04, respectively, p = 0.02). In patients with VUR and RS, LL-37/creatinine was significantly lower (p = 0.01). LL-37/creatinine with an AUC of 0.71 and NGAL/creatinine with an AUC of 0.72 could be acceptable diagnostic tests for severe VUR. In conclusion, urinary IL-6, NGAL, and LL-37 could serve as valuable markers for diagnosing and predicting outcomes in patients with VUR and RN.